Instrument for sensing magnetic variations in the atmosphere



FIG. 1 is a perspective view of an instrument for sensing magnetic variations in the atmosphere showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a typical side elevational view thereof; and

FIG. 4 is a bottom plan view thereof. 

The ornamental design for an instrument for sensing magnetic variations in the atmosphere, as shown. 